Honestly at her age she is not old enough to do more than help someone look after one. Which means if you do loan one you will have to pay for full livery or do it yourself.

I would suggest you take some stable management lessons. You will then see if you are prepared for the commitment owning a pony needs and will be able to teach her yourself

I've had horses all my life but find the work involved with my horse and two of my daughters to be hard, especially in winter.

Even young teenagers shouldn't really be left in sole charge of a pony IMO, in fact our yard insists on an adult being present for under 16's